# Omango
This is a concurrency collection.
- Support lock-free SPSC and MPMC queue (bounded and unbounded).
The queues are simple, lightweight, fast and safe in multithreading environment.
It is faster than [std::mpsc::sync_channel](https://github.com/rust-lang/rust/tree/master/library/std/src/sync/mpsc)
and other open source's bounded queue (
[ringbuf](https://github.com/agerasev/ringbuf),
[rtrb](https://github.com/mgeier/rtrb),
[flume](https://github.com/zesterer/flume),
[crossbeam-channel](https://github.com/crossbeam-rs/crossbeam/tree/master/crossbeam-channel)
).
- Support `Golang WaitGroup` waits for a collection of threads to finish.
- Support `Single Flight` multiplexing threads that have the same work and
only one represent thread will run and returns response for all waiting threads.
- Support `Single Source` provide mechanism to synthesize response from multiple
sources.
## Table of Contents
- [Introduction](#introduction)
- [Usage](#usage)
- [Compatibility](#compatibility)
- [Benchmarks](#benchmarks)
- [License](#license)
- [Reference](#refecence)
## Introduction
Both `SPSC` and `MPMC` queue are implemented based on pseudocode of [Dmitry Vyukov](https://docs.google.com/document/d/1yIAYmbvL3JxOKOjuCyon7JhW4cSv1wy5hC0ApeGMV9s/pub).
The implementation way is exactly the same. But there are still some differences between them about wait-retry and blocking.
`MPMC` is high contention multithreading environment. If the retry is continuous and immediate, the CPU cache coherence
will be increased rapidly and decrease performance. Therefore, we must wait then retry.
However, this thing is unsuitable in `SPSC` is lower contention multithreading environment (Just 2 threads).
In `SPSC`, the immediate retry still guarantees performance.
Both `SPSC` and `MPMC` queue can be used as channels.
#### Compared with version 0.1.*
* Performance is better.
* Supported unbounded queues (SPSC + MPMC).
* Can use `recv` to get remaining items when the queue was closed.
## Usage
Add this to your `Cargo.toml`:
```toml
[dependencies]
omango = "0.2.6"
```
## Compatibility
The minimum supported Rust version is `1.57`.
## Benchmarks
Tests were performed on an Intel Core I7 with 4 cores running Windows 11 and
M1 with 8 cores running macOS BigSur 11.3.
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## License
The crate is licensed under the terms of the MIT
license. See [LICENSE](LICENSE) for more information.
## Reference
* [Crossbeam-Channel](https://github.com/crossbeam-rs/crossbeam/tree/master/crossbeam-channel)
* [Blog of Dmitry Vyukov](https://docs.google.com/document/d/1yIAYmbvL3JxOKOjuCyon7JhW4cSv1wy5hC0ApeGMV9s/pub)
* [The cache coherence protocols](https://www.sciencedirect.com/topics/engineering/cache-coherence)
* [CppCon 2017: C++ atomics, from basic to advanced](https://www.youtube.com/watch?v=ZQFzMfHIxng)
* [Golang SingleFlight](https://github.com/golang/sync/blob/master/singleflight/singleflight.go)
* [Golang WaitGroup](https://github.com/golang/go/blob/master/src/sync/waitgroup.go)